Variable condenser



Oct. 12 1926.

F. SEELAU VARIABLE CONDENSER Filed Oct. 23, 192.4

lNVEN TOR E'Seelau BY 2 g j ATTORNEY Patented Get. 12, 1926.

UNITED STATES FRANK SEELAU, OF DETROIT, MICHIGAN.

VARIABLE CONDENSER.

Application filed October 23, 1.924.

The main object of this invention is the provision of a variable condenser, particularly adaptable to radio telephony.

Another object is to provide such a condenser having a fine, delicate. and accurate adjustment, the construction of the condenser permitting such accurate adjustment in a minimum of time.

In the case of most radio condensers, proper adjustment to the capacity of the circuit, for any given wave length and conditions, even when attainable. cannot be accomplished excepting with the utmost care, labor, and even skill, generally requiring an unnecessarily long time.

It is the aim of my invention to overcome the above and other defects of the variable condensers in common use at present, and to provide such a condenser in which the capacity may be increased or decreased over a wide range with great accuracy in a minimum of time.

Another object is to provide a plurality of condenser plates within the shell. each plate connected to a separate terminal insulated from the shell, so that each plate or any group may be used as one pole. thus allowing a still greater degree of variation.

The above and other objects will become apparent in the description below, in which reference characters refer to like-named parts on the accompanying drawings.

Referring briefly to the drawings, Figure 1 is an end view, with the cover omitted, of my condenser.

Figure 2 is a front view of the same. with the outer shell or cover partly removed to show the interior.

Figure 3 is an end view, likewise with the outer shell or cover removed, of a moditied form of condenser.

Referring now in detail to the drawings, the condenser comprises, first. an enclosing wall or shell 10 which acts as one pole or plate of the condenser. shaped as shown. The curved upper and lower ends of said shell provide bases for attaching insulating blocks 11 and 12. Screw contact heads 13 protrude thru said blocks into the inner compartment of said shell, said heads extending from binding posts 14 having nuts 15 for securing lead wires thereto. Diagonally opposite ends of the insulating blocks 11 and 12 are bevelled as shown to provide a secure hold for plates 16 and 17. Said plates are, as shown, firmly gripped in the Serial No. 745,268.

said bevelled edges of the insulating blocks. Tongues 24 extend rigidly from said plates and are urged by means of springs 26 toward the center of the compartment, said springs being attached to collars of metal 2'? held between the head 13 and insulating blocks 11 and 12.

In the center of the compartment a shaft or spindle is mounted. Secured to said pindle, at its center. are adjacent eccentric drums or cams. rigid on the shaft, the shaft being rotatable: said drums are indicated by the reference numerals 18 and 19. The shaft 20 and the eccentric drums 18 are formed of some known conducting material such as hard rubber. The plates 16 and 17, being urged toward the center of the coinpartment, rest against said drums. The plate 16 is slotted at 21 to permit the drum 18 to protrude therethru without contact; likewise plate 17 is slotted to permit drum 19 to protrude therethru without contact. Thus, plate 16 rests against drum 19. and plate 17 against drum 18. The tongues 2 are formed by slotting and bending the slotted portion out of the plates. as shown at 25.

A binding post 29 is secured to the end wall 22 ot the shell, the head 28 thereof lying within the compartment, and having also the nut 30 for securing a lead wire.

The binding posts 14. connected with the plates 16 and 17. constitute one pole and the post 29. connected with the shell 10 and 22, the other pole. of the condenser. It is apparent that, upon rotation of the spindle in one direction. the plates 16 and 17 will separate from each other, and upon rotation of said spindle in the opposite direction. they will approach each other. Thereby the capacit between the shell and the plates can be varied to a minute degree.

In Figure the condenser is shown comprising a cylindrical shell 31 having rotatably mounted therein a spindle On opposite sides are attached. insulated from the shell. binding posts 37 having nuts 38. To the inner ends of said posts are secured contacts and 36. and to these are permanently attached spiral plates 33 and 34, the inner ends of the spirals being secured to diametrically opposite sides of the spindle 32. A third binding, post 39, having the nut 40. is attached to the shell 31. The post 39, connected with the shell 31, provides one pole of the condenser, and the posts 37, connected with the plates 33 and 34, the other. Here, again, it is apparent that the capacity between said plates and said shell may be minutely varied by rotating the spindle 352. It is to be further noted that additional variations of capacity may be obtained by using but one of the plates 33 and 34, or both, as a single pole. The same applies to the plates 16 and 17 of Figure 1.

Having thus described my invention, what I claim and desire to secure by Letters Patent, is as follows:

1. A device of the class described compris ing an outer shell constituting one pole, plates movably mounted within said shell constituting the other pole, a shaft rotatably mounted within said shell and passing between said plates, and means on said shaft whereby upon rotation of said shaft the distance between said plates and said shell is varied.

2. A device of the class described, comprising an outer shell constituting one pole, plates pivotally secured within said shell and constituting the other pole, means for urging said plates toward each other, a shaft rotatably mounted Within said shell, and means on said shaft whereby said plates are separated from each other upon rotation of said shaft.

3. A device of the class described comprising an outer shell constituting one pole, plates pivotally secured within said shell and constituting the other pole, means urging said plates toward each other, a shaft rotatably mounted within said shell between said plates, eccentric drums mounted on said shaft adjacent each other, said plates resting against said drums so that upon rotation of said shaft, said plates are moved with respect to each other,

4. A device of the class described comprising an outer shell, an electrical terminal connected therewith, plates pivotally secured within said shell, electrical terminals connected each with one of said plates and insulated from said shell, a shaft rotatably mounted within said shell, and means on said shaft whereby said plates are separated from each other upon rotation of said shaft.

In testimony whereof I affix my signature.

FRANK s'EELAU. 

